1 /* 2 * linux/drivers/char/misc.c 3 * 4 * Generic misc open routine by Johan Myreen 5 * 6 * Based on code from Linus 7 * 8 * Teemu Rantanen's Microsoft Busmouse support and Derrick Cole's 9 * changes incorporated into 0.97pl4 10 * by Peter Cervasio (pete%q106fm.uucp@wupost.wustl.edu) (08SEP92) 11 * See busmouse.c for particulars. 12 * 13 * Made things a lot mode modular - easy to compile in just one or two 14 * of the misc drivers, as they are now completely independent. Linus. 15 * 16 * Support for loadable modules. 8-Sep-95 Philip Blundell <pjb27@cam.ac.uk> 17 * 18 * Fixed a failing symbol register to free the device registration 19 * Alan Cox <alan@lxorguk.ukuu.org.uk> 21-Jan-96 20 * 21 * Dynamic minors and /proc/mice by Alessandro Rubini. 26-Mar-96 22 * 23 * Renamed to misc and miscdevice to be more accurate. Alan Cox 26-Mar-96 24 * 25 * Handling of mouse minor numbers for kerneld: 26 * Idea by Jacques Gelinas <jack@solucorp.qc.ca>, 27 * adapted by Bjorn Ekwall <bj0rn@blox.se> 28 * corrected by Alan Cox <alan@lxorguk.ukuu.org.uk> 29 * 30 * Changes for kmod (from kerneld): 31 * Cyrus Durgin <cider@speakeasy.org> 32 * 33 * Added devfs support. Richard Gooch <rgooch@atnf.csiro.au> 10-Jan-1998 34 */ 35 36 #include <linux/module.h> 37 #include <linux/config.h> 38 39 #include <linux/fs.h> 40 #include <linux/errno.h> 41 #include <linux/miscdevice.h> 42 #include <linux/kernel.h> 43 #include <linux/major.h> 44 #include <linux/slab.h> 45 #include <linux/proc_fs.h> 46 #include <linux/seq_file.h> 47 #include <linux/devfs_fs_kernel.h> 48 #include <linux/stat.h> 49 #include <linux/init.h> 50 #include <linux/device.h> 51 #include <linux/tty.h> 52 #include <linux/kmod.h> 53 54 /* 55 * Head entry for the doubly linked miscdevice list 56 */ 57 static LIST_HEAD(misc_list); 58 static DECLARE_MUTEX(misc_sem); 59 60 /* 61 * Assigned numbers, used for dynamic minors 62 */ 63 #define DYNAMIC_MINORS 64 /* like dynamic majors */ 64 static unsigned char misc_minors[DYNAMIC_MINORS / 8]; 65 66 extern int rtc_DP8570A_init(void); 67 extern int rtc_MK48T08_init(void); 68 extern int pmu_device_init(void); 69 70 #ifdef CONFIG_PROC_FS 71 static void *misc_seq_start(struct seq_file *seq, loff_t *pos) 72 { 73 struct miscdevice *p; 74 loff_t off = 0; 75 76 down(&misc_sem); 77 list_for_each_entry(p, &misc_list, list) { 78 if (*pos == off++) 79 return p; 80 } 81 return NULL; 82 } 83 84 static void *misc_seq_next(struct seq_file *seq, void *v, loff_t *pos) 85 { 86 struct list_head *n = ((struct miscdevice *)v)->list.next; 87 88 ++*pos; 89 90 return (n != &misc_list) ? list_entry(n, struct miscdevice, list) 91 : NULL; 92 } 93 94 static void misc_seq_stop(struct seq_file *seq, void *v) 95 { 96 up(&misc_sem); 97 } 98 99 static int misc_seq_show(struct seq_file *seq, void *v) 100 { 101 const struct miscdevice *p = v; 102 103 seq_printf(seq, "%3i %s\n", p->minor, p->name ? p->name : ""); 104 return 0; 105 } 106 107 108 static struct seq_operations misc_seq_ops = { 109 .start = misc_seq_start, 110 .next = misc_seq_next, 111 .stop = misc_seq_stop, 112 .show = misc_seq_show, 113 }; 114 115 static int misc_seq_open(struct inode *inode, struct file *file) 116 { 117 return seq_open(file, &misc_seq_ops); 118 } 119 120 static struct file_operations misc_proc_fops = { 121 .owner = THIS_MODULE, 122 .open = misc_seq_open, 123 .read = seq_read, 124 .llseek = seq_lseek, 125 .release = seq_release, 126 }; 127 #endif 128 129 static int misc_open(struct inode * inode, struct file * file) 130 { 131 int minor = iminor(inode); 132 struct miscdevice *c; 133 int err = -ENODEV; 134 struct file_operations *old_fops, *new_fops = NULL; 135 136 down(&misc_sem); 137 138 list_for_each_entry(c, &misc_list, list) { 139 if (c->minor == minor) { 140 new_fops = fops_get(c->fops); 141 break; 142 } 143 } 144 145 if (!new_fops) { 146 up(&misc_sem); 147 request_module("char-major-%d-%d", MISC_MAJOR, minor); 148 down(&misc_sem); 149 150 list_for_each_entry(c, &misc_list, list) { 151 if (c->minor == minor) { 152 new_fops = fops_get(c->fops); 153 break; 154 } 155 } 156 if (!new_fops) 157 goto fail; 158 } 159 160 err = 0; 161 old_fops = file->f_op; 162 file->f_op = new_fops; 163 if (file->f_op->open) { 164 err=file->f_op->open(inode,file); 165 if (err) { 166 fops_put(file->f_op); 167 file->f_op = fops_get(old_fops); 168 } 169 } 170 fops_put(old_fops); 171 fail: 172 up(&misc_sem); 173 return err; 174 } 175 176 /* 177 * TODO for 2.7: 178 * - add a struct kref to struct miscdevice and make all usages of 179 * them dynamic. 180 */ 181 static struct class *misc_class; 182 183 static struct file_operations misc_fops = { 184 .owner = THIS_MODULE, 185 .open = misc_open, 186 }; 187 188 189 /** 190 * misc_register - register a miscellaneous device 191 * @misc: device structure 192 * 193 * Register a miscellaneous device with the kernel. If the minor 194 * number is set to %MISC_DYNAMIC_MINOR a minor number is assigned 195 * and placed in the minor field of the structure. For other cases 196 * the minor number requested is used. 197 * 198 * The structure passed is linked into the kernel and may not be 199 * destroyed until it has been unregistered. 200 * 201 * A zero is returned on success and a negative errno code for 202 * failure. 203 */ 204 205 int misc_register(struct miscdevice * misc) 206 { 207 struct miscdevice *c; 208 dev_t dev; 209 int err; 210 211 down(&misc_sem); 212 list_for_each_entry(c, &misc_list, list) { 213 if (c->minor == misc->minor) { 214 up(&misc_sem); 215 return -EBUSY; 216 } 217 } 218 219 if (misc->minor == MISC_DYNAMIC_MINOR) { 220 int i = DYNAMIC_MINORS; 221 while (--i >= 0) 222 if ( (misc_minors[i>>3] & (1 << (i&7))) == 0) 223 break; 224 if (i<0) { 225 up(&misc_sem); 226 return -EBUSY; 227 } 228 misc->minor = i; 229 } 230 231 if (misc->minor < DYNAMIC_MINORS) 232 misc_minors[misc->minor >> 3] |= 1 << (misc->minor & 7); 233 if (misc->devfs_name[0] == '\0') { 234 snprintf(misc->devfs_name, sizeof(misc->devfs_name), 235 "misc/%s", misc->name); 236 } 237 dev = MKDEV(MISC_MAJOR, misc->minor); 238 239 misc->class = class_device_create(misc_class, dev, misc->dev, 240 "%s", misc->name); 241 if (IS_ERR(misc->class)) { 242 err = PTR_ERR(misc->class); 243 goto out; 244 } 245 246 err = devfs_mk_cdev(dev, S_IFCHR|S_IRUSR|S_IWUSR|S_IRGRP, 247 misc->devfs_name); 248 if (err) { 249 class_device_destroy(misc_class, dev); 250 goto out; 251 } 252 253 /* 254 * Add it to the front, so that later devices can "override" 255 * earlier defaults 256 */ 257 list_add(&misc->list, &misc_list); 258 out: 259 up(&misc_sem); 260 return err; 261 } 262 263 /** 264 * misc_deregister - unregister a miscellaneous device 265 * @misc: device to unregister 266 * 267 * Unregister a miscellaneous device that was previously 268 * successfully registered with misc_register(). Success 269 * is indicated by a zero return, a negative errno code 270 * indicates an error. 271 */ 272 273 int misc_deregister(struct miscdevice * misc) 274 { 275 int i = misc->minor; 276 277 if (list_empty(&misc->list)) 278 return -EINVAL; 279 280 down(&misc_sem); 281 list_del(&misc->list); 282 class_device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor)); 283 devfs_remove(misc->devfs_name); 284 if (i < DYNAMIC_MINORS && i>0) { 285 misc_minors[i>>3] &= ~(1 << (misc->minor & 7)); 286 } 287 up(&misc_sem); 288 return 0; 289 } 290 291 EXPORT_SYMBOL(misc_register); 292 EXPORT_SYMBOL(misc_deregister); 293 294 static int __init misc_init(void) 295 { 296 #ifdef CONFIG_PROC_FS 297 struct proc_dir_entry *ent; 298 299 ent = create_proc_entry("misc", 0, NULL); 300 if (ent) 301 ent->proc_fops = &misc_proc_fops; 302 #endif 303 misc_class = class_create(THIS_MODULE, "misc"); 304 if (IS_ERR(misc_class)) 305 return PTR_ERR(misc_class); 306 #ifdef CONFIG_MVME16x 307 rtc_MK48T08_init(); 308 #endif 309 #ifdef CONFIG_BVME6000 310 rtc_DP8570A_init(); 311 #endif 312 if (register_chrdev(MISC_MAJOR,"misc",&misc_fops)) { 313 printk("unable to get major %d for misc devices\n", 314 MISC_MAJOR); 315 class_destroy(misc_class); 316 return -EIO; 317 } 318 return 0; 319 } 320 subsys_initcall(misc_init); 321